健康与遗传心理学研究室知识库

    创伤后应激障碍(Post-traumatic stress disorder, PTSD)是指个体在经历或者目睹对生命有威肋、或严重伤害的创伤事件之后导致的长期持续的精神疾患。在众多PTSD的影响因素中，社会因素发挥着重要的作用，其中社会交往被认为是决定个体在经历创伤事件之后是否出现心理健康问题最重要的心理社会因素之一。因此，理解社会环境的作用有助于更好的认识PTSD。社会网络理论为研究者考察社会环境与PTSD的关系提供了新的视角。在社会网络中个体与个体是相互依赖的，并且相互提供情感、信息、物质等方面的交流，因此网络中的社会关系能够缓冲创伤事件对个体造成的伤害从而影响PTSD的发生、发展和转归。以往对社会网络的研究通常只关注个体的社会网络规模以及关系类型多元化(个体网)与PTSD症状的关系，这就忽略了网络位置以及网络结构(整体网)的作用。因此，本研究试图从整体网的角度出发，探讨社会网络在PTSD发生发展过程中的变化，以及不同阶段的社会网络与PTSD样症状之间的关系。
    实验一采用重复测量的方法探讨应激对群居大鼠社群结构的影响。结果发现，应激能够改变大鼠的社会结构，在应激后的当天晚上大鼠被动社会交往行为增加(例如，聚集在一起休息)，而主动社会交往行为减少(例如，嗅闻、追随等等)。然而异常的社会结构指标(集群个数、单只个数、积极社会交往时间、社会距离)在应激后7天就恢复到了正常水平。另外，结果还发现，在行为测试阶段，异常的社会结构再次出现，社会行为的增加或减少受当天行为测验性质的影响。
    实验二采用社会网络分析的方法探讨PTSD发生发展各个阶段的社会网络与PTSD样行为之间的关系。结果发现，应激当天的社会网络与PTSD样行为之间的关系最为紧密，应激当天处在社会网络中心的个体，日后发展出的焦虑水平、快感缺失水平、恐惧水平较低。另外，由于代偿作用，自发恢复阶段的网络与PTSD样行为的关系和其他阶段相反，焦虑水平、恐惧水平越高的个体通过寻求社会交往缓解自己的异常症状，反而越处在网络中心位置。
    实验三试图探讨大鼠个性特征与PTSD发生发展不同阶段社会网络的关系。结果发现，在受到强烈应激时，大鼠的社会网络反映的是急性应激效应，并能够预测应激诱发的异常行为表现;但是在没有外界刺激的情况下以及急性应激期过后的自我调适阶段，大鼠社会网络的建构主要依赖于其个性特征;
    实验四探讨亲缘关系是否会影响社会网络的建立。结果发现，大鼠具有亲缘识别的能力，并且在焦虑状态下，大鼠更倾向于和自己的亲兄弟建立社会联结。
    总之，应激处理能够改变大鼠的社会网络，并且社会网络一直处于动态变化中，不同阶段的网络与PTSD样行为的关系也不同。

   Post-traumatic stress disorder (PTSD) is a mental disorder that involves the development of long-lasting symptoms following exposure to a traumatic event.Social interaction is considered as one of the most important psychosocial factors that determine whether an individual will have mental health problems following stressor exposure. Social network is a framework that integrates all kinds of social interactions so that it's usually used to describe the social environment around an individual.Previous studies have indicated that social network plays an important role in the prevention and recovery of PTSD. However, most of the available studies mainly focused on the egocentric network. For example, the protective effects of large size and high diversity of social support network. Little is known about the effects of global network structure on PTSD. We thus investigated how single prolonged stress (SPS)  impacts  the  spatiotemporal  social  structure  within  a  large  crowd  of co-habituated Sprague-Dawley rats and the relationship between social network and PTSD symptoms.
   In the first study, 16 rats were housed together in a large custom-made cylinder throughout the experimental procedure and underwent the SPS procedure two weeks after their arrival. We used an automatic tracking system to record social interactions within this large crowd of rats for 36 consecutive days. The results showed that social dynamics were modulated after acute stress. Stress induced closeness among rats.Although this unusually high level of closeness returned to the control level quickly, a fear- and  anxiety-like oscillatory pattern of the  social behavioral abnormalities re-emerged during a subsequent series of behavioral tests.
    In the second study, social network analysis was used to explore the role of social  network  in  the  development  of  PTSD  symptoms.  According  to  the developmental stage of PTSD, we divided social network into 6 time periods including pre-stress days, the stress day, early phase of acute stress period, late phase of acute stress period, spontaneous recovery period and test days. The results showed that rats' PTSD-like symptoms most relevant to the social network of the stress day.On the night of rats underwent SPS treatment, the individuals who in the center of the network were less likely to have PTSD-like symptoms. In addition, because of compensatory action, in the spontaneous recovery period, the individuals with high level of anxiety were more likely to have more social connections.
    The third study was to explore the relationship between individual personalities and social network. Results showed that on days before stress, P6-7, the spontaneous recovery period and test days, rats with lower anxiety sensitivity, conditioned fear responses in the fear conditioning test and higher reward sensitivity were more likely in the center of the network. However, on the night of rats underwent SPS treatment,their  social  network  was  mainly  influenced  by  the  acute  stress  effect.  The relationships between individual personalities and social network were prevented.
    The fourth study was to explore the influence of kin selection on social networks.We found that in the spontaneous recovery period, rats were more likely to interact with their littermates.
    In conclusion,  SPS treatment causally influenced the spatiotemporal social structure. There were dynamic changes in the relationship between social network and PTSD-like symptoms, and the network of the stress day played the greatest role in predicting later PTSD-like symptoms. Individuals who were pushed to outer edges of the network on the stress day were more likely to develop PTSD-like symptoms later.